Anti-cockroach activities of biosynthesized silver nanoparticles using Petiveria alliacea extracts

Abstract

Background

This study was conducted with a view to biosynthesize silver nanoparticles (AgNPs) using the root (PaR) and leaf (PaL) extracts of Petiveria alliacea and evaluation of their activities against cockroaches, which is a major household insect pest.

Methods

The biosynthesized AgNPs were characterized by UV–Vis spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX). PaR-AgNPs and PaL-AgNPs were tested at three different concentrations (1, 5, 10% v/v) using two modes of applications (fumigant and contact toxicity) at different hours of exposure.

Results

The peak absorbance of the AgNPs occurred at the wavelengths of 426 and 442 nm for PaL-AgNPs and PaR-AgNPs, respectively, with the brownish colloidal solutions. FITR peaks indicated the presence of alkenes (= C–H), esters (= O), amides (= N–H), and aliphatic amines (= C–N) in the samples, while the TEM and EDX analyses showed the presence of silver in the AgNPs colloidal solution, with the spherical nanoparticles ranging from 5.95 to 76.19 nm in size. Both AgNPs demonstrated insecticidal action against adult cockroaches, with the fumigant application causing more rapid death than the contact application. The fumigant application resulted in 80–90% cockroach mortality, while the contact application caused 40–50% mortality after three hours of exposure at 10% v/v. These results demonstrate that the effectiveness of the bio-fabricated AgNP formulations depends on the concentrations, hours of exposure, and mode of application.

Conclusion

Therefore, the pest management program for household pests, particularly cockroaches, can incorporate silver nanoparticle-based insecticides.

Article Highlights

• TEM and EDX analyses indicate the presence of silver in the nano-insecticide products

• Biosynthesized AgNPs exhibited insecticidal action against adult cockroach

• Toxicity effect of nano-insecticides depends on mode of application

• Nano-insecticides applied through fumigant killed faster than when applied through contact

• Effectiveness of biosynthesized AgNPs was dose-dependent